Logistics Reduction: Heat Melt Compactor (LR-HMC)

The Advanced Exploration Systems (AES) Logistics Reduction (LR) project Heat Melt Compactor (HMC) technology is a waste management technology. Currently, there are no waste management practices that are being implemented in the space environment other than manual compaction of waste into a plastic bag. The current practice does not recover critical resources such as water, does not prevent the growth of potentially harmful microbiological pathogens, and provides only limited volume reduction.

The primary purpose of the HMC is to reduce the volume and microbiologically stabilize the waste. The HMC is a device that compacts and heats the trash. The trash is heated to the point where some of the plastic softens and fills the interstitial voids between non-melted trash. The compacted trash is then cooled, resulting in a dry, relatively solid tile that does not exhibit the spring back of traditional compactors. The shape of the tile is predictable and maximizes the efficiency of storage volume. When the trash is heated, it results in a microbiologically-safe tile that can be safely handled by the crew. The HMC can process both wet and dry trash. The water that is driven off the waste is collected and returned to the Water Recovery System. The tiles have ~10% hydrogen by mass from the plastics, wipes, and residual food and can be used to provide additional radiation shielding in the spacecraft.

A full-scale, second-generation (Gen2) HMC has been developed and is being used to finalize operational parameters and identify hardware issues. Gen2 HMC tests will allow development of an eventual ISS flight unit. Several SBIR awards related to HMC have occurred in the following areas: microgravity-compatible condensing heat exchanger designs, trash bag liners to allow hygienic tiles after HMC processing, and general HMC system design. 

Limited Gen2 HMC ground testing began in 2017 but was not completed due to inability to reach desired compaction pressure and vacuum.  In FY18 the hardware was repaired to partially restore its desired capability.  Ground testing is planned in FY19 to investigate the use of the ISS vent system as a possible simplification of product gas treatment.  In FY18, procurement planning of a commercially-developed HMC (named the Trash Compaction and Processing System - TCPS) began with a FY19 award planned for preliminary design and a ground prototype.  The TCPS procurement is under NASA's NextSTEP BAA contract.  A second phase NextSTEP procurement is planned for development of a TCPS flight unit for ISS is planned for delivery in 2023.